cat, read – catenate files|
cat [ file ... ]|
read [ –m | –n nlines | –c nbytes | –r nrunes ] [ file ... ]
Cat reads each file in sequence and writes it on the standard
If no file is given, cat reads from the standard input. Output is buffered in blocks matching the input.
Read copies to standard output exactly one line from the named file, default standard input. It is useful in interactive rc(1) scripts.
The –m flag causes it to continue reading and writing multiple lines until end of file; –n causes it to read no more than nlines lines. The –c and –r flags specify a number of bytes or runes to read instead of lines.
When reading lines, read always executes a single write for each
line of input, which can be helpful when preparing input to programs
that expect line–at–a–time data. It never reads any more data from
the input than it prints to the output.
Read exits with status eof on end of file or, in the –n case, if
it doesn't read nlines lines.|
Beware of cat a b >a and cat a b >b, which destroy input files before